This invention relates to laminated packaging materials designed for use as lids for high density polyethylene and/or polypropylene cups. More particularly, it relates to a lidding material comprising a co-extruded layer of ethylene methyl acrylate and low density polyethylene resin, a layer of polyester, a layer of low density polyolefin resin, and a layer of metallic foil.
Food products, particularly beverages and other materials having high liquid content, are increasingly being sold in containers made of high density polyethylene and/or polypropylene. One of the principal uses for containers of this type is for the sale of food products for on-premises or off-premises comsumption. For ease of handling, particularly when the containers or cups are filled at a location other than that in which the product is sold, the cups are sealed with a lidding material. Such lidding material may consist of a molded lid made out of a high density polyethylene or polypropylene material similar to or identical to the container material, molded so as to provide a slot adapted to receive the upper rim of the container. Lids of this nature, however, often do not fit tightly enough and, as a result, there is some spillage of the beverage during transport. There has therefore been developed an alternate type of lidding material, namely a laminated structure and one or more additional film layers. Typically, this laminated structure, which is adhered to the top of the beverage container by the use of heat and pressure, seals the top of said container and has a protruding tab so that the lid can be easily removed. In many instances, however, grasping of the tab results in only partial removal of the lid because the lid itself is torn. Use of a weaker adhesive substance would diminish the likelihood of tearing the lid but would serve effectively to protect the contents of the beverage container.
It is therefore a principal object of this invention to provide a metallic foil based lidding material of sufficient strength so that, upon removal, a lid made therefrom will separate from the container without tearing. It is a further object of this invention to provide a lidding material which is not substantially thicker than metallic foil based lidding materials currently in use. These, and further objects of the invention will be more apparent from the following description.